'The Besieged Ego' critically appraises the representation, or mediation, of identity in contemporary film and television shows through a thorough analysis of split and fragmentary characters. As I show, the prevalence of nonautonomous characters in horror, fantasy and psychological based film and television products calls into question the very concept of a unified, 'knowable' identity that can be traced progressively through time with continuity. I use psychoanalysis as an interpretive tool and model in order to effectively understand representations of identity that are not 'whole'; psychoanalysis arguably allows for, and engages with, a splintered or fractured identity as its very premise lies in unknowable psychical forces such as the unconscious. The concept of 'ego' is particularly useful as a concept through which to analyse onscreen representations of identity; the differing definitions of Freud's ego (realist and narcissistic) alongside Lacan's delusional ego allow for an understanding of identity that shifts and is deeply enigmatic, unknowable and in essence confusing. However, representations of split identities can only be fully examined in light of social and cultural contexts; I therefore employ an eclectic range of approaches and methodologies throughout the thesis in order to ascertain what is at stake in the representation and meaning of the double. The form of the double, and cinematic modes and rhetorics used to denote fragmentary identity, is addressed in the thesis through a detailed analysis of texts drawn from a range of industrial and cultural contexts. The double carries significant cultural meanings about what it means to be 'human' and the experience of identity as a gendered individual; I argue that the double, or split identity, has become a 'new myth' that expresses in fictional form our problematic experience of the world as a social, and supposedly whole and autonomous, subject.